Pressure responsive switch with actuator pivotal about different axes for low and high pressure actuation

ABSTRACT

A switch for a pumping system turns a pump off whenever pressure in the accumulator increases above a first level or drops below a second level and allows the pump to run at accumulator pressures intermediate such first and second pressure levels. A pressure responsive switch actuator pivots about one pivot axis in response to a high pressure condition and another, spaced pivot axis in response to a low pressure condition. In both cases the same switch is actuated. A manual override is also provided.

United States Patent Hartley [451 Mar. 21, 1972 [54] PRESSURE RESPONSIVE SWITCH WITH ACTUATOR PIVOTAL ABOUT DIFFERENT AXES FOR LOW AND HIGH PRESSURE ACTUATION Ezra D. Hartley, 2700 Jalmia Drive, Los Angeles, Calif. 90046 July 2, 1970 Inventor:

Filed:

Appl. No.:

US. Cl. ..200/81 R, 200/83 R, 200/83 S, 200/83 Z Int. Cl ..H0lh 35/24, H01h 35/34 Field of Search ..200/81 R, 82 R, 83 R, 83 S, 200/8l.9 R,81HO, 83 J, 83Z

Ill/[I'll 1mm We WFSFESQFLKL. UNITED STATES PATENTS 2,741,677 4/1956 Clendenin "200/33 R Primary Examiner-Robert K. Schaefer Assistant Examiner- Robert A. Vanderhye Attorney-Smyth, Roston and Pavitt ABSTRACT a a Whimsfilirsrles 5192a.

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Ezra D. Hartley ,5 M law (/2012? y ATTORNEYS PRESSURE RESPONSIVE SWITCH WITH ACTUATOR PIVOTAL ABOUT DIFFERENT AXES FOR LOW AND HIGH PRESSURE ACTUATION BACKGROUND OF THE INVENTION Pumping systems typically include a source of liquid, a pump for pumping the liquid from the source to a preselected destination and control means for operating the pump. In many pumping systems, such as in a pumping system utilized for providing water in a recreational vehicle, the control means turns the pump on in response to the pressure downstream of the pump dropping to a predetermined low level and turns the pump off when the downstream pressure reaches a desired maximum level. It is also desirable for the control means to turn the pump off in the event that system pressure drops below a preset minimum. This is necessary in the event that the source of liquid in the supply tank becomes exhausted or in the event of a leak in the system. If the pump were not shut down under these circumstances, it would run continuously and may become damaged or destroyed.

One way of accomplishing such a control function is to employ two separate pressure switches, one having a high pressure cutoff capability and the other having a low pressure cutoff capability. Switches which are available for performing both the high pressure and low pressure cutoff functions are generally quite complex.

If the supply of liquid in the supply tank becomes exhausted, the conduit between the inlet of the pump and the storage tank becomes filled with a column of air. The conduit between the pump outlet and the outlet of the liquid system contains a column of water and, perhaps, some air. When the supply tank is again filled with liquid, the pump pumps the air at the inlet thereof; however, it may not develop sufficient pressure downstream of the pump to overcome the static head of water in the conduit between the pump outlet and the outlet of the liquid supply system. Normally even a self-priming pump will be unable to do this.

SUMMARY OF THE INVENTION The present invention provides a pumping system including several novel features each of which is particularly adapted for use in a pumping system of the type normally employed in recreational vehicles such as mobile homes, campers, trailers, etc. However, many of the features of this invention find utility in other environments.

The present invention provides a fluid pressure responsive switch of simple, inexpensive construction which shuts the pump motor off in response to high pressure or low pressure conditions and causes the pump motor to operate at intermediate pressure levels. This advantageous result is accomplished by providing an actuator member and shiftable means for mounting the actuator member for pivotal movement about two pivot axes. When the fluid pressure being sensed is in a first pressure range, the actuator member pivots about the first pivot axis and when the fluid pressure being sensed is in a second range lower than the first range, the actuator member pivots about the second pivot axis. The pump motor is turned off in response to pivoting to predetermined positions about either of the pivot axes.

The actuator member is moved by a pressure responsive member in a first direction in response to an increase in fluid pressure and in a second direction in response to a decrease in fluid pressure. An advantage of the double pivot axes is that the same output motion can be obtained from the actuator member in either a high pressure or low pressure situation. In order to obtain the same output motion for high pressure and low pressure conditions, the pressure responsive member should apply a force to a region of the actuator member intermediate the two pivot axes. It is a simple matter to provide means responsive to such output motion of the actuator member to deenergize the pump motor and such means may be contact between a portion of the actuator member and the button of a switch. Of course, for intermediate pressure levels,

the actuator member permits the switch to close the cause the pump motor and pump to operate.

The actuator member is preferably exposed so that it can easily be manually moved to its low pressure cutoff position to thereby prevent the pump motor and pump from running. If this is done with the outlet of the system, which may include, for example, a conventional water tap, being open, the pressure in the system downstream of the accumulator will drop to substantially zero. The system will remain in this condition until it is manually reset by manually moving the actuator member to start the pump.

To facilitate pump priming in the event the system runs dry, the present device provides for automatically opening a conduit between the accumulator and the pump in response to a preselected low pressure condition. The open conduit allows the water in the accumulator and the water in the system to drain back to or through the pump. This should be done with the system outlet, e.g., a water faucet open to thereby provide an air vent for the system. Draining of the water back to the pump provides water for priming of the pump and in addition allows the water to continuously recirculate between the pump and accumulator until the air in the system has been pumped out through the open faucet. The air can be pumped out because it need not force any water out ahead of it.

The present device also provides a self-cleaning filter for the pump and a large reservoir for accumulation of debris which is removed from the filter. This can be accomplished by mounting the pump on a body and with the body at least partially defining an inlet section. The inlet section includes a bottom wall and the filter is placed substantially horizontally in the inlet section above the bottom wall and beneath the pump inlet so that water supplied to the inlet section must flow through the filter. Because the filter is in a horizontal position, debris collecting on the underside thereof tends to fall under the influence of gravity to the bottom wall of the inlet section with the space between the filter and the bottom wall serving as a reservoir for the collection of debris.

The several elements of this device can be advantageously mounted on, or be formed at least in part, by an integral body. In a preferred form of the invention, the pump is mounted on the body, and the body forms a part of the accumulator as well as at least portion of the conduits interconnecting the pump and accumulator. The body is arranged so that the conduits carrying relatively low pressure liquid circumscribe the conduits carrying higher pressure liquid so that in the event the high pressure conduit ruptures, it will drain into the low pressure compartment where it can be contained.

The invention, both as to its organization and method of operation together with further features and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying illustrative drawings in which:

FIG. 1 is a schematic view of a liquid system containing the switch of the present invention.

FIG. 2 is a plan view of a pumping system constructed with the switch of the present invention.

FIG. 3 is a fragmentary sectional view taken generally along line 3-3 of FIG. 2.

FIG. 4 is a sectional view taken generally along line 4-4 of FIG. 3.

FIG. 5 is a sectional view taken generally along line 5-5 of FIG. 2 and showing the pressure responsive switch of the present invention in an intermediate pressure range condition in which the pump motor is running.

FIG. 5a is a sectional view similar to FIG. 5 showing the pressure switch in a high pressure cutoff condition.

FIG. 5b is a sectional view similar to FIG. 5 showing the pressure switch in a low pressure cutoff condition.

FIG. 6 is a sectional view taken generally along line 6-6 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings and in particular to FIG. 1 thereof, reference numeral 11 designates a liquid supply system having a pumping system 13 may be utilized in other environments and for other fluids.

The system 1 1 includes a supply tank 15 for supplying water through a conduit 17 to the pumping system 13. The pumping system 13 supplies liquid under pressure through a conduit 19 to a water distribution system 23 which may include the usual water distribution elements such as a water valve or faucet 25. The water distribution system 23 may also be supplied with water from a second source (not shown) such as a city water system through a check valve 27.

As shown in FIGS. 2 and 3 the pumping system 13 generally includes a body 29, a pump 31 mounted on the body, an electric motor 33 for driving the pump, an accumulator 35 and a pressure switch 37. Generally the pump 31 which is driven by the motor 33 receives water through an inlet 39 (FIGS. 2 and 4) and supplies same to an outlet 41 through the accumulator 35. The pressure switch 37 turns the motor 33 off in response to high pressure or low pressure conditions in the accumulator 35 and allows the motor to run when the pressure within the accumulator is at intermediate levels. The pumping system 13 will normally be mounted in the horizontal position shown in FIG. 1.

The body 29 which is of intricate shape as shown in FIGS. 3 and 4 is preferably integrally molded from a suitable plastic material. The body 29 provides an annular upstanding, mounting flange 43 into which the pump 31 is slidably received, the pump being suitably attached to the body 29 as by screws (not shown) which project through a flange 44 integral with the pump 31 and mounting bosses 44a (FIG. 4a) formed integrally as part of the body 29. The pump 31 is preferably a positive displacement, roller pump; however, other pump constructions can be utilized. The motor 33 is preferably mounted directly on the pump 31 and is an electric motor. The pump 31 and the motor 33 are encased by an upstanding, annular flange 45 and a hollow end cap 47 suitably releasably connected to the flange 45.

The body 29 has an irregularly shaped platform 48 (FIGS. 2 and 4) and an outer peripheral wall 49 (FIG. 4) depending from, and integral with, the platform 48. A bottom plate 51, which may be constructed of metal (FIG. 3) is releasably attached to the peripheral wall 49 by a plurality of screws 53 which can be received in bosses 54 (FIG. 4). A gasket 55 is sandwiched between the plate 51 and the peripheral wall 49. Except for cutout regions which are necessary to allow liquid flow, the gasket 55 is substantially coextensive with the body 29. The body 29 has an inner wall 57 integral with the platform 48 which circumscribes an area within the peripheral wall 49. The body 29 also has a wall 59 (FIG. 4) integral with the platform 48 defining an outlet conduit 61 leading away from the accumulator 35. The walls 57 and 59 depend from the platform 48 and sealingly engage the gasket 55 at their lower ends. The body has a plurality of generally radially extending reinforcing ribs 63, each of which depends from, and is integral with, the platform 48 and terminates short of the gasket 55. The mounting bosses 44a are also integral with the platform 48.

The area enclosed by the peripheral wall 49 outside of the walls 57 and 59 forms an inlet section 64 and is supplied with liquid from the inlet 39 (FIGS. 2 and 4). The liquid entering the inlet 39 flows across one ofthe reinforcing ribs 63 (FIG. 4) to apertures 65 in the platform 48 (FIGS. 3 and 4) of the body. The apertures 65 are in direct communication with the inlet of the pump 31.

A filter 64a (FIGS. 3 and 6) which may be in the form of a screen is mounted generally horizontally in the inlet section 64. The filter is spaced upwardly from the bottom gasket 55 and the plate 51. The filter 64a lies above or substantially flush with (in the normal position of the system 13 shown in FIG. 3) the lower end of the adjacent reinforcing ribs 63 so that all the water flowing from the inlet 39 to the inlet of the pump 31 must flow through the filter 64a. The filter 64a extends along a region of the peripheral wall 49 and terminates at the ribs 63 nearest the pump 31. The filter 64a is cleaned by gravity and the relatively large volume inlet section 64 forms a large volume reservoir for debris which falls off of the filter. Thus. cleaning of the system 13 is held to a minimum.

The pump draws the water through the apertures 65 and discharges it through apertures 69 which provide communication between the outlet of the pump 31 and a passage 71 defined by the wall 57 (FIG. 4). The passage 71, like the inlet section 64 and the conduit 61, has its upper end integrally closed by the platform 48 and its lower end closed by the gasket 53 and the plate 51. The passage 71 leads to a plurality of circularly arranged openings 73 in a portion of the platform 48 forming a bottom wall 75 of the accumulator 35. The accumulator 35 includes an upstanding annular flange 77 (FIG. 3) integral with the body 29 and a concave end cap 79 constructed of plastic material and attached to the body by a bolt 81 and a nut 83. As the accumulator 35 should be sealed, an annular seal 85 is positioned between the mating surfaces of the flange 77 and the end gap 79.

The openings 73 are closed by a check valve which includes a flexible washer or valve element 87 which is preferably constructed of rubber or similar material. The valve element 87 surrounds the bolt 81 and is adapted to sealingly engage the valve seat or surface of the bottom wall 75 which surrounds each of the openings 73. With the system 13 operating, the pump supplies water at sufficient pressure to unseat the valve element 87 and to compress air within the accumulator 35 against the upper portion of the accumulator. The pressure within the accumulator 35 acts on the valve element 87 to urge the latter tightly against the bottom wall 77 to prevent backflow of the water in the accumulator toward the pump 31.

In order to automatically drain the accumulator 35 in response to a low pressure condition therein, a spring 89 is provided in one of the apertures 73 with the spring acting between the valve element 87 and an annular shoulder 91 formed integrally with the body 29 within the passage 71. The spring 89 urges a portion of the valve element 87 upwardly away from the apertures 73 in which the spring is located. The force of the spring 89 is selected so that when the pressure of liquid within the accumulator is above a preset level, the pressure within the accumulator 35 urges the valve element against the wall 75 to close the apertures 73 and to cause the valve element 87 to act as a check valve. However, when the pressure in the accumulator drops below a preset level such as the low pressure cutoff point, the spring 89 urges a portion of the valve element away from the associated opening 73 to permit flow of liquid in the accumulator 35 into the passage 71 toward the pump outlet. Such a low pressure condition may occur, for example, if the supply tank 15 is pumped dry.

The bottom wall 75 of the accumulator 35 has a port 93 (FIG. 4) therein which provides communication between the accumulator and the conduit 61. The other end of the conduit 61 communicates with the outlet 41 to thereby provide a flow path between the accumulator 35 and the outlet 41. The gasket 55 is held tightly against the lower end of the wall 59 by the plate 51 so that fluid under pressure leaving the accumulator cannot leak into the inlet section 64. However, should a leak occur in the conduit 61, the high pressure fluid therein would merely drain into the inlet section 64 rather than out of the entire pumping system. Accordingly, no liquid would be lost and no mess would be created as a result of such break. Similarly, any leak in the wall 57 which defines the passage 71 would result in leakage into the inlet section 64 rather than to a location external to the pumping system 13.

The body 29 has a wall section 95 (FIG. 4) depending from and integral with the platform 48 which joins spaced regions of the wall 57 and defines therewith a pressure chamber 97 (FIGS. 3 and 5). The pressure chamber 97 is supplied with fluid under pressure from the accumulator 35 through a restricted orifice 99, a passage 101 (FIG. 3) in an enlarged or thickened portion of the wall 57 and a passage 102 defined by an elongated dimple or channellike section 103 of the plate 51. The channel section 103 is quite narrow and on opposite sides thereof, the gasket 53 is sealingly clamped between the plate 51 and adjacent regions of the wall 57 to prevent escape of the liquid into the passage 71 or the inlet section 64. The gasket 55 is appropriately cut away so as not to interfere with this flow path between the accumulator 35 and the pressure chamber 97. The function of the restricted orifice 99 is to impose some time delay between the occurrence of a pressure change in the accumulator 35 and the occurrence of a similar pressure change in the pressure chamber 97.

The details of the pressure switch 37, of the present invention, can best be seen from FIGS. 2, 3 and 5. The pressure switch 37 includes a plunger 105 mounted for reciprocating movement in the pressure chamber 97 with the upper end of the plunger projecting upwardly through an opening in the upper end of the pressure chamber. The plunger 105, which may be integrally molded from plastic material, is urged downwardly by a coil compression spring 107 which bears against an annular shoulder 109 at the upper end of the pressure chamber 97. A rolling diaphragm 111 covers the lower end of the pressure chamber 97 and has an enlarged annular seal 113 formed integrally with the outer periphery thereof. The seal 113 is clamped in an annular groove in the walls 57 and 95 by the plate 51 and the gasket 55. The diaphragm 111 is constructed of a resilient material such as rubber, The plunger 105 has an upwardly facing annular shoulder 115.

The pressure switch 37 also includes an actuator member 117 which is connected to the plunger 105 by a screw 119. The actuator member 117, which may be integrally molded from plastic material, has an opening 121 therein which is defined by webs 122 each of which has an arcuate ,upper surface 122a and an arcuate lower surface l22b. The opening 121 loosely receives a neck portion 123 of the plunger 105.

The actuator member 117 has a protruding curved surface defining a fulcrum 125 which is adapted to rest on an abutment 127 formed integrally with the body 29. The actuator member 117 also has an aperture 129 through which a screw 131 loosely extends and is received in the body 29. The head of the screw 131 is engageable with an arcuate shoulder or fulcrum 132.

The actuator member 117 has an end portion 133 adapted to engage a depressible button 135 of a conventional switch 137 which is suitably mounted on the body 29. The switch 137 is coupled by suitable circuitry (not shown) to the motor 33 so that when the button 135 is depressed, the circuit to the motor is open and the pump 31 will not run. Conversely, when the end portion 133 of the actuator member 117 does not depress the button 135, a spring (not shown) within the switch 137 moves the button 135 outwardly to the position shown in FIG. 5 thereby closing the switch and the circuit to the pump motor 33.

In operation of the pressure switch 37, the diaphragm 111 is exposed to the same pressure as the water in the accumulator 35 subject, however, to the time delay interposed by the orifice 99. Specifically, water in the accumulator is transmitted through the orifice 99, the passage 101 and the passage 102 formed by the channel section 103 to the outer face of the diaphragm. With the plunger 105 in the position shown in FIG. 5, the switch 135 is closed and the motor 33 is operating.

With the pump 31 running, fluid under pressure is supplied by the pump through the aperture 69 (FIGS. 3 and 4), a passage 71 (FIG. 4) and the openings 73 (FIGS. 3 and 4) to the accumulator 35. If the faucet 25 is open, water flows through the port 93 (FIG. 4), the conduit 61, the outlet 41 and the conduit 19 (FIG. 1) to the faucet 25. When the faucet 25 is turned off, the pump continues to supply water to the accumulator 35 and this results in a pressure increase in the accumulator. The pressure increase is sensed by the plunger 105 with the result that the plunger 105 is moved upwardly against a biasing force of the spring 107. When the surface 122b engages the shoulder 115 of the plunger 105, further upward mulator. The diaphragm 111 and the plunger sense the pressure decrease and the spring 107 is operative to move the plunger downwardly. The actuator member 117 pivots downwardly about the fulcrum 132 toward the position shown in FIG. 5 under the influence of its own weight and/or the head of the screw 119. This results in an upward movement of the end portion 133 of the actuator member 117 with consequent upward movement of the button 135 to close the switch 137 and start the pump motor 33. Thus, normal operation of the pressure switch 37 will occur as shown in FIGS. 5

. and 5a. Of course, the particular pressure at which the switch 135 opens and closes can be selected to meet design requirements.

The motor 33 is turned off when the button 135 is depressed sufficiently to open the switch 137, and the pump is turned on when the button is elevated by the spring within the switch sufficiently to close the switch. Thus, the pressure differential between starting and stopping the motor 33 is a function of the switch 137 and the time delay between pressure change and switch actuation. The pressure at which the switch 137 is actuated can be varied by turning of the screw 131. By unscrewing the screw 131 to move the head thereof further away from the body 29, the pressure at which the pump is turned on and off will be increased. The high pressure cutoff pressure can be decreased by turning the screw 131 in the opposite direction so that the head thereof is moved closer to the body 29. Preferably the pressure switch 137 is arranged to cycle the motor 33 on when the faucet 15 is opened and to turn the motor off shortly after the faucet is closed.

The pressure switch 37 operates as shown in FIG. 5b to open the switch 137 in response to an excessively low pressure such as may occur if the supply tank 15 is pumped dry or if a leak should occur resulting in complete loss of supply water. Should such a low pressure condition occur, the spring 107 urges the plunger 105 downwardly toward the position illustrated in FIG. 5b. The head of the screw 119 engages the curved shoulder 122a of the actuator member 117 thereby drawing the actuator member downwardly. However, downward movement of the fulcrum 125 is arrested by the abutment 127 whereupon further downward movement of the plunger and of the actuator member causes the actuator member to pivot about the fulcrum 125. The generous clearance spaces between the opening 121 and the neck portion 123 and between the aperture 129 and the screw 131 allows this pivotal movement to occur. A loss of pressure results in clockwise movement of the actuator member about the fulcrum 125 with the result that the end portion 133 moves against the button to open the circuit to the motor. Thus, the actuator member 117 pivots about the fulcrum 132 when the pressure within the accumulator 35 is in a high pressure range and about the fulcrum 125 when the pressure in the accumulator is in a low pressure range.

This low pressure cutoff condition may occur at any selected pressure such as, for example, 2 p.s.i. This low pressure cutoff point can be varied by adjusting the screw 119. Thus, by unscrewing the screw 119 to move the head thereof further away from the neck portion 123, the low pressure cutoff point is reduced and conversely by turning the screw 119 to move the head closer to the neck portion 123, the low pressure cutoff point is increased.

By providing two separate fulcrums or pivot axes for the actuator member 117, the end portion 133 can be caused to move along basically the same path in response to either a high pressure or a low pressure condition to thereby actuate the switch 137 by depressing the button 135. This is also the result, in part, of applying the motive force to the actuator member 117 at a location intermediate the fulcrums 125 and 132.

Once the low pressure condition of the type shown in FIG. b has occurred, the pump can only be manually restarted by depressing the end portion 139 (FIG. 5b) of the actuator member to cause the latter to pivot counterclockwise about the fulcrum 125 thereby releasing the button 135 and closing the circuit to the motor 33. Once sufficient pressure has been built up by the pump 31 in the accumulator 35 to avoid the low pressure cutoff condition, the pump will thereafter be cycled on and off automatically by the pressure switch 37. An advantage of the manual reset feature is that if the system is to remain inactive for a long period of time, the user can hold the actuator member 117 in the low pressure cutoff condition shown in FIG. 5b with the faucet 25 opened until the pressure in the accumulator 35 drops to the low pressure cutoff point. In this event, the system can only be manually reset as described above.

Typically the faucet 25 is at a location above the pump 31 so that the pump must overcome a static head of water. If the tank is pumped dry, there is a column of air in the conduit 17 (FIG. 1) between the tank and the inlet to the pump 31. When the tank 15 is refilled, this column of air may remain in the conduit 17. In this event, the pump would ordinarily be pumping air and attempting to compress the air sufficiently to overcome the static head in the conduit 19 between the outlet of the pump and the faucet 25. Even a self priming pump will probably not be able to accomplish this.

With the present invention, the spring 89 is responsive to a preset low pressure condition in the accumulator 35 such as the low pressure cutoff point to hold one of the openings 73 open by lifting the valve element 87 off of such opening as shown in FIG. 3. With the faucet open, the water in the accumulator drains back into the passage 71 and toward the pump outlet. Similarly the water in the conduit 19 can drain into the accumulator and from there into the conduit 71. The water draining back toward the pump may actually reach the pump inlet and serve to prime the pump. In any even, the open faucet 25 provides an open path or vent which allows any air pumped by the pump to escape. Ultimately, all the air will be pumped out of the system, and thereafter, the pump 13 will operate normally to supply water from the tank 15.

The specific embodiment shown can be modified in many different ways. For example, the body 29 can be a configuration different than the one illustrated. The pressure switch 37 is usable in other environments, e.g., a compressed air system.

Although an exemplary embodiment of the invention has been shown and described, many changes, modifications, and substitutions may be made by one having ordinary skill in the art without necessarily departing from the spirit and scope of this invention.

Iclaim:

1. A pressure switch operable in response to fluid pressure comprising:

an actuator member;

first releasable means for mounting said actuator member for pivotable movement about a first pivot axis;

second releasable means for mounting said actuator member for pivotable movement about a second pivot axis, said pivot axes being spaced;

fluid pressure responsive means responsive to a change in the fluid pressure for applying a force to said actuator member tending to move said actuator member;

means responsive to the fluid pressure being in a first pressure range for releasing said second means whereby the actuator member pivots about said first pivot axis in response to said force;

means responsive to the fluid pressure being in a second pressure range for releasing the first means whereby the actuator member pivots about said second pivot axis in response to said force, at least some of the pressures of said first pressure range being higher than the pressures of said second pressure range;

a switch;

means responsive to said actuator member pivoting about said first pivot axis to a first predetermined position corresponding to a first pressure of the fluid for actuating said switch; and

means responsive to said actuator member pivoting about said second pivot axis to a second predetermined position corresponding to a second pressure of the fluid for actuating said switch, said first and second pressures being different whereby said switch is actuated in response to said fluid being at either of said first or second pressures.

2. A pressure switch as defined in claim 1 wherein said pivot axes are generally parallel, said pressure responsive means applies said force to said actuator member intermediate said pivot axes.

3. A pressure switch as defined in claim 1 including means for adjusting the position of said first predetermined position whereby the magnitude of said first pressure can be adjusted.

4. A pressure switch as defined in claim 1 wherein the actuation of said switch when the actuator member is in said first predetermined position places the switch in a first state, said pressure switch including means responsive to the actuator member being in a third position corresponding to a third pressure of the fluid for causing said switch to assume a second state different from said first state, the actuation of said switch by said actuator member at said second pressure of the fluid returning said switch to said first state, said first pressure being higher than said second pressure and said third pressure being intermediate first and second pressures.

5. A pressure switch as defined in claim 1 including a body, said fluid pressure responsive member being mounted on said body, said first means includes an opening in said actuator member and a shaft projecting loosely through said opening and mounted on said body, said second means including an abutment on said body engageable with a region of said actuator member.

6. A pressure switch operable in response to fluid pressure comprising:

a fluid pressure responsive member;

means for mounting said fluid pressure responsive member for movement along a path in a first direction in response to the pressure of the fluid increasing and in a second direction along said path in response to the pressure of the. fluid decreasing, said directions being generally opposite;

an actuator member;

shiftable means for mounting said actuator member for pivotable movement about said first and second pivotal axes, said pivotal axes being spaced;

means for drivingly connecting said fluid pressure responsive member to said actuator member at a location generally intermediate said pivot axes;

said shiftable means including first means for mounting said actuator member for pivotal movement about said first pivotal axes in response to the pressure of the fluid being in a first range and second means for mounting the actuator member for pivotal movement about said second pivot axes in response to the pressure of the fluid being in a second range, at least a substantial number of the pressures in said second range being less than the pressures of said first range whereby movement of said fluid pressure responsive member in said first direction when said actuator member is mounted for pivotal movement about said first pivot axis pivots said actuator member in one direction and movement of said fluid pressure responsive member in said second direction when said actuator member is mounted for pivotal movement about said second pivot axes pivots said actuator member in said one direction; and

means responsive to pivotal movement of said actuator member in said one direction about either of said pivot axes for performing a switching function.

said first and second means includes a body member having a stop thereon for engaging said actuator member at a predetermined region to thereby arrest further movement of said region in a predetermined direction. 

1. A pressure switch operable in response to fluid pressure comprising: an actuator member; first releasable means for mounting said actuator member for pivotable movement about a first pivot axis; second releasable means for mounting said actuator member for pivotable movement about a second pivot axis, said pivot axes being spaced; fluid pressure responsive means responsive to a change in the fluid pressure for applying a force to said actuator member tending to move said actuator member; means responsive to the fluid pressure being in a first pressure range for releasing said second means whereby the actuator member pivots about said first pivot axis in response to said force; means responsive to the fluid pressure being in a second pressure range for releasing the first means whereby the actuator member pivots about said second pivot axis in response to said force, at least some of the pressures of said first pressure range being higher than the pressures of said second pressure range; a switch; means responsive to said actuator member pivoting about said first pivot axis to a first predetermined position corresponding to a first pressure of the fluid for actuating said switch; and means responsive to said actuator member pivoting about said second pivot axis to a second predetermined position corresponding to a second pressure of the fluid for actuating said switch, said first and second pressures being different whereby said switch is actuated in response to said fluid being at either of said first or second pressures.
 2. A pressure switch as defined in claim 1 wherein said pivot axes are generally parallel, said pressure responsive means applies said force to said actuator member intermediate said pivot axes.
 3. A pressure switch as defined in claim 1 including means for adjusting the position of said first predetermined position whereby the magnitude of said first pressure can be adjusted.
 4. A pressure switch as defined in claim 1 wherein the actuation of said switch when the actuator member is in said first predetermined position places the switch in a first state, said pressure switch including means responsive to the actuator member being in a third position corresponding to a third pressure of the fluid for causing said switch to assume a second state different from said first state, the actuation of said switch by said actuator member at said second pressure of the fluid returning said switch to said first state, said first pressure being higher than said second pressure and said third pressure being intermediate first and second pressures.
 5. A pressure switch as defined in claim 1 including a body, said fluid pressure responsive member being mounted on said body, said first means includes an opening in said actuator member and a shaft projecting loosely through said opening and mounted on said body, saiD second means including an abutment on said body engageable with a region of said actuator member.
 6. A pressure switch operable in response to fluid pressure comprising: a fluid pressure responsive member; means for mounting said fluid pressure responsive member for movement along a path in a first direction in response to the pressure of the fluid increasing and in a second direction along said path in response to the pressure of the fluid decreasing, said directions being generally opposite; an actuator member; shiftable means for mounting said actuator member for pivotable movement about said first and second pivotal axes, said pivotal axes being spaced; means for drivingly connecting said fluid pressure responsive member to said actuator member at a location generally intermediate said pivot axes; said shiftable means including first means for mounting said actuator member for pivotal movement about said first pivotal axes in response to the pressure of the fluid being in a first range and second means for mounting the actuator member for pivotal movement about said second pivot axes in response to the pressure of the fluid being in a second range, at least a substantial number of the pressures in said second range being less than the pressures of said first range whereby movement of said fluid pressure responsive member in said first direction when said actuator member is mounted for pivotal movement about said first pivot axis pivots said actuator member in one direction and movement of said fluid pressure responsive member in said second direction when said actuator member is mounted for pivotal movement about said second pivot axes pivots said actuator member in said one direction; and means responsive to pivotal movement of said actuator member in said one direction about either of said pivot axes for performing a switching function.
 7. A pressure switch as defined in claim 6 wherein one of said first and second means includes an opening in said actuator member, a shaft projecting through said opening and means for mounting said shaft, said aperture loosely receiving said shaft.
 8. A pressure switch as defined in claim 6 wherein one of said first and second means includes a body member having a stop thereon for engaging said actuator member at a predetermined region to thereby arrest further movement of said region in a predetermined direction. 